If the issue doesn't get fixed by troubleshooting or changing the USB ports, you can follow the below mentioned steps to resolve it.
- Before you take a look at the USB connection make sure you are using a USB 2.0 port.
- Do not forget to update the version of iTunes
- Take a high power USB 2.0 port and connect your device directly to it. Make sure you do not plug in the device into standalone or a keyboard hub.
- Remove the accessory from the dock and by using apple USB Dock Connector cable, plug it in to the computer.
- Restart your device as well as your computer.
- Except for your mouse and keyboard, disconnect the USB devices from your computer. In the end you will connect your iOS device, if the connection is successful, test it after each connection.
If the above mentioned procedure does not work then follow the course of actions stated below:
- After making sure that your device is in the Recovery Mode, connect your device with iTunes.
- After restoring wait for the error and click OK when it appears.
- Do not disconnect your device. Close the iTunes application and then reopen it.
- In the Recovery Mode the device will get recognition.
- In the end again restore.